Method for operating a drive unit of an electric bicycle

Abstract

The present invention relates to a method for operating a drive unit for an electric bicycle, wherein the drive unit includes a motor and at least one transmission device mechanically coupled to the motor, wherein the transmission device has at least one gear pair including a first gear and a second gear, and wherein the motor operates in a noise reduction mode so as to achieve contact of the forward tooth sides of the gears by a determined relative torque between the first gear and the second gear.

Description

Technical Field

[0001] The present invention relates to a method for operating a drive unit for an electric bicycle, a drive unit for an electric bicycle, and an electric bicycle. Background Technology

[0002] An electric bicycle with a drive unit is known, which is configured to generate motor torque to assist the rider's manual pedaling force. Typically, a transmission mechanism for changing the rotational speed of the motor is provided between the motor that generates the torque and the crankshaft, usually connected to the chainring. This transmission mechanism usually has multiple meshing gears. Especially when the load on the chain changes alternately (e.g., when riding on uneven surfaces or when the rear shock spring of a fully suspended bicycle is compressed), noise, such as clicking, is generated on the gears due to the impact of the gear teeth flanks. Summary of the Invention

[0003] The method according to the invention, having the features of claim 1, is characterized by its ability to achieve particularly low-noise operation of the drive unit of an electric bicycle. In particular, it is able to reduce or avoid noise generated in the transmission due to the impact of tooth flanks. This is achieved according to the invention by a method for operating the drive unit of an electric bicycle, wherein the drive unit comprises a motor and at least one transmission mechanically coupled to the motor. Preferably, the motor and transmission are coupled such that the motor can transmit torque to the transmission, and preferably the transmission subsequently drives other components of the electric bicycle (e.g., crankshaft, especially chainring). Here, the transmission has at least one gear pair having a first gear and a second gear. In the method, the motor operates in a noise-reducing mode, characterized by: controlling the operation of the motor so as to achieve contact of the forward tooth flanks of the gears through a defined relative torque between the first and second gears (especially always).

[0004] Specifically, the following tooth flanks of the gears are considered as the forward tooth flanks: the tooth flanks of the gears that mesh (i.e., mechanically contact) when a predetermined torque is transmitted in the forward rotation direction via the transmission device. Preferably, the forward rotation direction is defined as: the motor torque generated by the motor is suitable for assisting the forward movement of the electric bicycle when torque is transmitted from the motor via the transmission device.

[0005] Preferably, in the noise reduction operating mode, the motor is alternatively or additionally manipulated in such a controlled manner that a predetermined torque transmission from the first gear to the second gear is always achieved only in the positive direction of rotation. Particularly preferably, the motor here always provides a predetermined relative torque (especially positive torque) from the first gear to the second gear.

[0006] In other words, the method provides a noise-reducing operating mode, which is preferably executed at least for a limited time. In this noise-reducing operating mode, the motor of the drive unit is selectively and controllably manipulated such that a defined relative torque between the gears of the transmission provides a mechanical preload to the transmission, causing the same tooth flanks (i.e., the forward tooth flanks of the gears) in the transmission to always be in contact with each other. That is, tooth flank backlash is compensated in the same direction, especially through the particularly targeted operation of the motor. In other words, the first gear is slightly braked relative to the housing of the drive unit, making it difficult for the forward tooth flanks to disengage, i.e., preventing disengagement rotation of the forward tooth flanks.

[0007] The advantage of this method is that it can compensate for transmission backlash in a particularly simple and cost-effective manner (i.e., through targeted, preferably software-based, control of the drive unit's motor). This reduces or completely eliminates unwanted tooth flank switching caused by rotational vibrations on the chainring (e.g., when traveling on uneven surfaces and / or due to rear shock spring compression). In particular, by ensuring the motor operates with the forward tooth flank of the gear always in a targeted manner, clicking noise caused by overcoming transmission backlash can be avoided. Furthermore, the method also has the advantage of achieving improved motor (i.e., especially motor-assisted) response performance by effectively transmitting torque without overcoming transmission backlash.

[0008] The dependent claims illustrate preferred extensions of the invention.

[0009] Preferably, the noise reduction operating mode is implemented only during the riding operation of the electric bicycle. Particularly preferably, the noise reduction operating mode is implemented only during the forward movement of the electric bicycle. The riding state, especially forward movement, can be determined based on sensors, and the method is implemented in response to this riding state. Therefore, it is possible to provide the electric bicycle rider with energy-efficient operation with extremely high comfort.

[0010] Particularly preferably, the noise-reducing operation mode is implemented outside the drive unit's auxiliary mode, and especially only outside the drive unit's auxiliary mode. The auxiliary mode is characterized by generating motor torque to assist the electric bicycle's forward movement. In other words, the noise-reducing operation mode is not executed during the active motor assistance phase of the drive unit's auxiliary mode. This allows for optimal assistance in the riding state without obstruction through the generated motor torque. For example, in the auxiliary mode, by generating auxiliary motor torque, torque transmission from the motor via the transmission is spontaneously initiated, causing the gear's forward tooth side to engage.

[0011] Preferably, the noise-reducing operating mode (especially for predetermined time periods) is implemented immediately before and / or after each use of the assist mode. In other words, by selectively manipulating the motor in the noise-reducing operating mode, backlash in the transmission is overcome immediately before and / or after each use of the motor in assist mode. This provides optimal response performance of the motor with the aid of motor torque. That is, the motor can provide motor torque particularly directly for assisting the forward movement of the e-bike. Furthermore, noise generated due to the impact of different tooth flanks in the transmission can be reliably avoided, thereby providing extremely high riding comfort.

[0012] More preferably, the noise reduction operating mode includes: controlled manipulation of the motor to brake the rotation of the motor rotor in the opposite direction of rotation. Preferably, the rotation in the opposite direction of rotation can be identified by means of a rotor position sensor, and braking is preferably performed in response to the identification of the rotation in the opposite direction of rotation. In other words, the motor rotor is braked, i.e., decelerated, in a targeted manner by controlled manipulation of the motor. Here, this braking is used to specifically induce the contact of the forward tooth side of the transmission gear. For example, rotation in the opposite direction of rotation is induced by a corresponding chain tension (e.g., possibly due to travel on uneven surfaces). This allows for particularly simple and reliable noise reduction during drive unit operation.

[0013] Preferably, rotor braking is achieved through controlled operation of the motor as a generator. That is, the motor operates to generate current as a generator. The force required to rotate the motor rotor causes rotor braking. This allows for particularly simple and efficient targeted engagement of the forward gear side. Additionally, current can be recovered by operating the motor as a generator, and this current can be stored, for example, in the electric bicycle's energy storage device. Therefore, particularly advantageous and efficient operation of the electric bicycle is possible.

[0014] Preferably, rotor braking is achieved by generating a predetermined constant braking torque. This allows braking to be performed in a particularly simple manner. Alternatively, motor braking is preferably achieved using a variable braking torque, which is preferably adapted to the reverse rotational speed of the current rotor. For example, in this case, braking can be determined based on the rotational speed according to a predetermined set of characteristic curves of the target braking torque. Thus, a particularly targeted and efficient method for operating the drive unit can be provided.

[0015] More preferably, the noise-reducing operating mode includes the following steps: the motor rotor is controlled to rotate by a predetermined rotation angle. Preferably, the predetermined rotation angle is at least 3°, more preferably at least 5°, and particularly preferably a maximum of 15°. That is, in the method, the motor rotor is selectively rotated by a small angle in the positive rotation direction (e.g., at a specific time point and / or in response to a predetermined operating state, such as immediately before and / or after the auxiliary mode). This ensures, in a particularly simple manner, that the forward tooth side of the gear is brought into contact as frequently as possible for low-noise operation.

[0016] Preferably, the noise-reducing operating mode includes the following steps: controlling the generation (especially a predetermined) of a gear meshing torque, which is preferably a maximum of 10 Nm, more preferably a maximum of 3 Nm, and especially at least 1 Nm. Preferably, this gear meshing torque is generated outside of the auxiliary mode. In other words, in the method, the motor is manipulated in a targeted manner (e.g., at specific points in time and / or in response to a predetermined operating state) so that it generates a small torque in the positive rotation direction so as to always be in contact with the forward tooth side as much as possible. Here, the gear meshing torque is small enough not to drive the chain.

[0017] Furthermore, the present invention relates to a drive unit for an electric bicycle, comprising a motor (especially an electric motor), at least one transmission device mechanically (especially in a torque-transmitting manner) coupled to the motor, and a control unit. The transmission device has at least one gear pair including a first gear and a second gear. The control unit is configured to perform the described method for operating the drive unit.

[0018] Preferably, the drive unit further includes a crankshaft configured for connection to the crank of an electric bicycle. Here, a transmission mechanism mechanically couples the motor to the crankshaft. That is, the motor torque generated by the motor can be transmitted to the crankshaft via the transmission mechanism. Furthermore, the crankshaft can be driven by the pedaling force of the electric bicycle rider via the crank.

[0019] Preferably, the drive unit further includes a freewheel (Freilauf) arranged between the motor and the crankshaft. The freewheel can, for example, be directly arranged between a gear in the transmission and the crankshaft. In particular, the freewheel thus serves as a motor freewheel, enabling decoupling of the motor from the crankshaft. Preferably, the freewheel is constructed as a bidirectional freewheel, meaning it can be opened and closed in both directions of rotation. In this type of drive unit, this specific method is particularly advantageous in ensuring simple and low-noise operation.

[0020] Furthermore, the present invention relates to an electric bicycle, including the described drive unit. Attached Figure Description

[0021] An embodiment of the present invention will now be described in detail with reference to the accompanying drawings.

[0022] The attached diagram shows: Figure 1 A simplified schematic diagram of an electric bicycle, wherein a method for operating an electric bicycle according to a preferred embodiment of the present invention is performed; Figure 2 : Figure 3 A detailed view of a simplified schematic of the drive unit of an electric bicycle; Figure 3 : Figure 2 A detailed view of the drive unit.

[0023] Preferably, the same components, elements and / or units are given the same reference numerals in all the drawings. Detailed Implementation

[0024] Figure 1 A simplified schematic diagram of an electric bicycle 100 is shown, wherein a method for operating a drive unit 1 of the electric bicycle 100 according to a preferred embodiment of the present invention is performed.

[0025] The electric bicycle 100 includes a drive unit 1, which includes a motor 3, particularly an electric motor. The motor 3 can be powered by the electric energy storage device 109 of the electric bicycle 100.

[0026] The drive unit 1 is located in the area of ​​the pedal bearing of the electric bicycle 100. The motor torque generated by the motor 3 can provide motor assistance to the pedaling force generated by the rider's muscle force.

[0027] The rider's muscle power can be transmitted to the crankshaft 6 via a crank mechanism including crank 104. The crankshaft 6 extends along the crank axis. The first gear 41 of the transmission device 4 of the drive unit 1 (see [reference]) is arranged coaxially with the crankshaft 6. Figure 2 Motor 3 can transmit motor torque to crankshaft 6 through transmission device 4.

[0028] As in Figure 2 In the illustrated embodiment, the transmission device 4 preferably includes a total of four gears 41, 42, 43, and 44, which together form three gear pairs 4. The fourth gear 44, which is opposite to the first gear 41, is connected to the motor shaft 31 of the motor 3 in a torque-transmitting manner.

[0029] In order to decouple the motor 3 from the crankshaft 6, the drive unit 1 includes a freewheel 7, which is arranged between the crankshaft 6 and the first gear 41. The freewheel 7 is preferably constructed as a bidirectional freewheel, which can realize the blocking and releasing of rotation in two directions respectively.

[0030] Furthermore, the chain plate 107 is connected to the crankshaft 6 in a particularly torsion-resistant manner. When the crankshaft 6 rotates, the chain plate 107 can drive the chain 105, which in turn drives the rear wheel of the electric bicycle 100, thereby propelling the electric bicycle 100 forward.

[0031] The method for operating the drive unit 1 according to the present invention is implemented when the electric bicycle 100 is in motion, and the method is described below. Here, the method is preferably implemented only during the movement of the electric bicycle 100. In particular, it is implemented only when the electric bicycle 100 is traveling in the forward direction A (see...). Figure 1 The method is implemented when moving forward.

[0032] In particular, the method is implemented only outside of the drive unit 1's auxiliary mode, in which the drive unit 1 provides motor torque that directly, particularly in addition to the rider's pedaling torque, causes the electric bicycle 100 to move forward. Preferably, it is performed for predetermined time periods before and / or after each implementation of the auxiliary mode.

[0033] In the method described, motor 3 operates in a noise-reducing mode, which is designed to induce a specific relative torque between the first gear 41 and the second gear 42 of the transmission 2, such that the forward tooth sides 45 of the two gears 41 and 42 are always in contact (see also...). Figure 3 ).

[0034] Preferably, the motor 3 is operated such that all gears 41, 42, 43, 44 of each gear pair 4 of the transmission device 2 abut only on the front tooth side 45.

[0035] exist Figure 3 The image shows in more detail the special meshing of the forward tooth side 45 of gears 41 and 42. (See image for details.) Figure 3 As shown, the rearward tooth sides 47 of each tooth of gears 41 and 42, which are opposite each other in the direction of rotation, do not mesh with each other.

[0036] Preferably, the operation of motor 3 in noise-reducing mode is performed as frequently as possible during the riding of electric bicycle 100. This operation offers the advantage of achieving particularly low-noise and low-wear operation of drive unit 1. The noise-reducing operation mode causes the gear pair 4 of transmission 2 to be constantly pre-tensioned, such that the forward tooth sides 45 mesh with each other. This avoids the need to overcome transmission clearance between gear pair 4 during motor-assisted start-up, after which the forward tooth sides 45 may noisily collide. This situation is particularly problematic when electric bicycle 100 is riding on uneven surfaces and / or when the electric bicycle 100 is fully actuated during the compression and rebound of the shock absorber springs. This can cause chain 105 vibration, for example, when... Figure 2 The vibration is simplified and schematically illustrated by arrow 50. This vibration of the chain 105 causes the chain tension to alternately move in different directions, or at least briefly, in the opposite direction to the drive direction, which may, for example, cause the forward tooth sides 45 of gears 41 and 42 to disengage. By selectively maneuvering the motor 3 to engage the forward tooth sides 45, torque transmission can be achieved during subsequent motor operation without overcoming backlash. In addition to reduced noise, this also offers the advantage of a particularly direct response from the motor assistance.

[0037] In the first embodiment, the noise reduction operating mode includes controlling the motor 3 to brake the reverse rotation of the motor 3's rotor. This rotation can be identified, for example, using a rotor position sensor. That is, when chain tension causes the rotor of the motor 3 to rotate in the reverse direction, this rotation can be braked by targeted manipulation of the motor 3 using a braking torque. This braking torque is generated here by operating the motor 3 as a generator.

[0038] Here, braking can be performed using a constant braking torque or, alternatively, a variable braking torque, which is preferably adapted to the rotor’s current reverse speed based on a predetermined characteristic curve.

[0039] Preferably, the current generated by the motor 3 operating as a generator can be stored in the energy storage 109 of the electric bicycle 100, i.e., it is recycled.

[0040] By braking the rotor of motor 3 during reverse rotation, it is possible to achieve contact between the forward tooth sides 45 of gears 41 and 42 in a particularly simple and reliable manner.

[0041] In another embodiment, the noise reduction operating mode includes: the rotor of motor 3 is controlled to rotate by a predetermined rotation angle in the forward rotation direction. The predetermined rotation angle may correspond to at least 5°, for example. Preferably, this controlled rotation is performed before and / or after each auxiliary mode. Alternatively or additionally, this controlled rotation may be performed at specific time intervals during the operation of the electric bicycle 100. That is, the rotor of motor 3 periodically rotates forward by a small angle to overcome any possible transmission backlash and to ensure that the forward tooth side 45 is targeted for contact.

[0042] In another embodiment, the noise reduction operating mode includes: controlling the generation of a predetermined gear engagement torque, which is particularly small enough to avoid driving the chain 105 (i.e., the movement of the chain 105). Preferably, the gear engagement torque is a maximum of 3 Nm.

[0043] This allows for a simple and reliable method of keeping the forward tooth side 45 in contact with the target in a manner similar to controlling a predetermined rotation angle for forward rotation, thereby avoiding or minimizing any impact on the movement of the electric bicycle 100.

[0044] It should be noted that the above-described embodiments of the method can be arbitrarily combined with each other. That is, each embodiment can be implemented independently. Alternatively, multiple embodiments can be executed simultaneously while the electric bicycle 100 is running.

Claims

1. A method for operating a drive unit (1) of an electric bicycle (100), - in, The drive unit (1) includes a motor (3) and at least one transmission device (2) mechanically coupled to the motor (3). - Wherein, the transmission device (2) includes at least one gear pair (4), the gear pair having a first gear (41) and a second gear (42), and - Wherein, the motor (3) operates in a noise reduction mode so as to achieve the contact of the forward tooth side (45) of the gears (41, 42) by a determined relative torque between the first gear (41) and the second gear (42).

2. The method according to claim 1, wherein, The noise reduction operating mode is implemented during the operation of the electric bicycle (100), especially during forward movement.

3. The method according to any one of the preceding claims, wherein, The noise reduction operating mode is implemented outside the auxiliary mode of the drive unit (1), and in particular only outside the auxiliary mode of the drive unit (1), in which motor torque is generated to assist the electric bicycle (100) to move forward.

4. The method according to claim 3, wherein, The noise reduction operation mode is implemented immediately before and / or after each implementation of the auxiliary mode, especially for predetermined time periods.

5. The method according to any one of the preceding claims, wherein, The noise reduction operation mode includes: controlling the motor (3) to brake the rotation of the rotor of the motor (3) in the opposite direction of rotation.

6. The method according to claim 5, wherein, The rotor is braked by the controlled operation of the motor (3) as a generator.

7. The method according to claim 5 or 6, wherein, Braking of the rotor (31) is achieved by means of the motor (3) generating a predetermined constant braking torque or a variable braking torque, wherein the variable braking torque is adapted according to the reverse rotation speed.

8. The method according to any one of the preceding claims, wherein, The noise reduction operation mode includes the following steps: the rotor of the motor (3) is rotated in a controlled manner by a predetermined rotation angle, which is in particular at least 3°, advantageously at least 5°, and preferably at most 15°.

9. The method according to any one of the preceding claims, wherein, The noise reduction operation mode includes the following steps: generating a controlled gear meshing torque, which is in particular a maximum of 10 Nm, preferably a maximum of 3 Nm, and in particular at least 1 Nm.

10. A drive unit for an electric bicycle (100), comprising: - Motor (3) - At least one transmission device (2) mechanically coupled to the motor (3). - Wherein, the transmission device (2) has at least one gear pair, the gear pair having a first gear (41) and a second gear (42), and - Control unit (10), the control unit being configured to perform the method according to any one of the preceding claims.

11. The drive unit according to claim 10, further comprising a crankshaft (6) for connection with a crank (104) of the electric bicycle (100), wherein, The transmission device (2) mechanically couples the motor (3) to the crankshaft (6).

12. The driving unit according to claim 11, characterized in that, It also includes a freewheel (7) arranged between the motor (2) and the crankshaft (6).

13. An electric bicycle, comprising a drive unit (1) according to any one of claims 10 to 12.

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